Method for the finishing of parts



May 3, 1966 H. G. VAN FossEN METHOD FOR THE FINISHING OF PARTS 2 Sheets-Sheet l Filed April 22, 1963 a A .flu emT F, Ky@ 4 im v 5 .o 2 \/f% :l

INVENTOR Han/e1., G Van Fossen May 3, 1966 H. G. VAN FossEN 3,248,825

METHOD FOR THE FINISHING OF PARTS 2 Sheets-Sheet 2 Filed April 22, 1963 INVENTOR. Marvel, G. Vcm Fossen BY United States Patent C)- 3,248,826 METHD FOR THE FINISHING F PARTS Harvey G. Van Fossen, Red Lion, Pa., assigner, by mesne assignments, to The Wheelabrator Corporation, Mishawaka, Ind., a corporation of Delaware Filed Apr. 22, 1963, Ser. No. 274,635 2 Claims. (Cl. 51-316) This invention relates to a method and apparatus for the finishing of metal parts and the like wherein such parts are disposed in a finishing medium and then subjected to vibration whereby the medium effects finishing of the surfaces. In particular, the invention is directed to an improved system wherein the parts to be finished and the medium are disposed in a vibratory bowl and maintained under unique conditions to effect the desired surface finishing.

It is a general object of this invention to provide an improved method for the finishing of parts by means of vibratory techniques which is characterized by extreme efiiciency in that the finishing can be completed rapidly and with a high degree of precision.

It is a more particular object of this invention to provide a system for the finishing of parts wherein the finishing operation can be completed in a relatively short time whereby polishing, deburring, fine finishing and the 3,248,826 Patented May 3, 1966 ICC FIGURE 7 is a sectional elevational view of a further alternative bowl structure characterized by the features of this invention; and,

FIGURE 8 is a sectional elevational view of a still futher alternative bowl structure characterized by the features of this invention.

The finishing system of this invention generally comprises a method for the finishing of parts wherein the parts are disposed in a bowl along with a finishing media and means are provided for vibrating the bowl. Pressure is then applied to the media and, accordingly, to the parts submerged therein and this pressure is maintained during vibration of the bowl whereby the parts are finished while subjected to pressure.

Various means may be employed to effect the desired pressure on the parts and media during the vibrating operation. The apparatus of this invention is generally characterized by a bowl having vibrating means associated therewith and having an at least partially open end with the media and submerged parts disposed within the bowl, pressure applying means are adapted to contact the surface of the combination of the parts and like can be undertaken in a highly economical and effective manner.

It is an additional object of this invention to provide a finishing system of the `type described which is adapted for use inv combination with finishing media which can be economically obtained but which are still effective to produce highly efficient finishing operations.

It is a further object of this invention to provide a finishing system of the type described which can be effectively employed with the use of lighter weight finishing media whereby pitting and nicking of the parts being finished can be greatly minimized.

It is a further object of this invention to provide a 'finishing system of the type described which is extremely versatile and which is adapted to be applied to parts heretofore considered unsuitable for finishing by vibratory techniques.

It is a further object of this invention to provide a finishing system of the type described which is capable of improving precision surface finishing in that internal deburring and polishing can be undertaken in a highly effective manner.

It is an additional object of this invention to prov-ide a finishing system of the typeA described which is capable of handling relatively small parts without a requirement for fixtures which have heretofore been employed to hold the parts in place within the vibrating bowl.

These and other objects of this invention will appear hereinafter and for purposes of illustration but not of limitation, specific embodiments of this invention are shown in the accompanying drawings in which:

FIGURE 1 comprises an elevational view partly in section of a vibratory bowl modified in accordance with the concepts of this invention;

FIGURE 2 is a detail sectional View of one alternative form of the invention;

FIGURE 3 is a detail sectional view of an additional alternative form of the invention;

FIGURE 4 is a detail sectional view of an additional alternative form of the invention;

FIGURE 5 is a detail sectional view of a still further alternative form of the invention;

FIGURE 6 is a sectional elevational view of an alternative vibratory bowl structure characterized by the features of this invention;

media through this open end. The forces applied by the pressure applying means are distributed throughout the combination of parts and media and these forces are adapted to be maintained during the vibrating operation.

The accompanying drawings illustrate various forms of mechanisms which 4may be utilized for achieving the objects of this invention. It will be understood that various previously disclosed types of vibratory finishing mechanisms may be employed in combination with the concepts of this invention and reference is made to the Brandt Patent No. 2,973,606 issued March 7, 1961, forl an illustration of a structure of the type contemplated.

FIGURE l illustrates a bowl 10 which defines an open end 12 and which is provided with a ru; ber liner 14. A flange member 16 extends downwardly from the bowl at one end and a similar fiange member will be associated with the bowl at its other end. An eccentric 18 is connected between these flange members and a drive shaft 20 provides for rotation of the fiange members to efiectthe desired vibration. Mounting plates 22 are provided at the sides of t-he bowl and springs 24 are located between these plates and a foundation 26.

Secured to the top of the bowl is a frame construetion 28 which is provided with a pressure applying piston 30 and associated cylinder 32. A cover 34 which is provided With rubber liner 36 is connected to the cylinde-r, and the finishing media 38 having parts 40 submerged therein is engaged by this cover. The liner 36 may be provided with overturned ends 42 to effect la seal between the rubber liner 14 and the cover. It will be apparent that with the arrangement illustrated in FIG- URE 1, force applied by means of the piston 30 to the cover 34 will be distributed to the surface of the media engaged by the cover. By maintaining the pressure of' the piston during the vibration of the bowl 10, finishing of the parts will take place under pressure. In FIGURE 2, Ia cover 44 having a rubber liner 46 is provided with a seat 48 which receives the end of a compression spring 50. The other end of the spring is fitted into a seat 52 which is attached to the frame 54 which is in turn attached to the top of the bowl 56 in the manner illustrated in FIGURE l. A seal between the liner 58 and the cover 44 can be effected by means of the return portions 60 defined by the cover.

The modification shown in FIGURE 3 is also effective for the application of pressure to the combination of parts and media disposed in a vibratory bowl. In this instance, a cover 62 is provided with a mounting plate sure over all portions of this surface.

provements in finishing operations.

3 64 which carries weights 66. A bolt 68 secured to the mounting plate cooperates with the nuts 70 to hold the weights firmly in place'dur-ing a vibrating operation.

In FIGURE 4 there is illustrated a screw 72 which is journalled at one end in a member 74 and which is threaded into the frame member 76 at its other end. Rotation of the screw Will provide for movement of the cover 78 whereby pressure can be applied to the contents of the vibratory bowl.

The modification shown in FIGURE includes a bowl 80 provided with a rubber liner 82 and having a cover plate 84 fastened at its upper end. The plate 8.4 is provided with a conduit 86 which is adapted to be associated with a source of air or other fiuid whereby pressure can -be applied to the upper surface of the cover 88. This cover will in turn transmit forces to the combination of parts and media disposed in the bowl whereby this c-ombination can be maintained under pressure duringV the vibrating oper-ation. A liner member 90 associated with `the cover 88 includes portions 92 which engage the liner 82 to effect a seal.

In the modification shown in FIGURE 6, the cover 94 is pivotally connected at 96 to the bowl 98. A plate 100 secured to the cover 94 provides a seat for the spring 102 whereby the cover 94 can be closed and pressed yaga-inst the contents of the bowl. It will be noted that the end 104 of the cover is not attached to the bowl and, accordingly, pressure can be applied in accordance with the compressive force of the spring 102. The liner 106 associated with the cover will cooperate with -the liner 108 of the bowl to provide the desired seal.

In FIGURE 7, the bowl 110 is providedwith a relatively narrow neck portion 112. A cover member 114 is adapted to be snugly received within the neck portion L12 and a screw 1.16 attached to this cover is adapted to provide for vertical adjustment of the cover within the neck 112. An arm 1718 is pivotally connected to the neck 1112 at 120 and the screw 116 passes through this arm. A latch 122 is adapted to engage flange 124 formed on Ithe neck portion to provide for locking of the plate 1,14 in a desired position.

FIGURE 8 illustrates a bowl 126 which is provided with a cover plate 128 which in turn is provided Wi@ a conduit 130 whereby fiuid pressure can be introduced into the space 132. A fiexible cover member 134 is provided for direct engagement with the combination of the media 136 and the par-ts 13S disposed therein. It will be apparent that the cover 134 will automatically assume the contour developed by the upper surface of this combination and will provide for uniform application of pres- With this arrangement, the combination of media and parts can be loaded into the bowl 126 and the cover 134 can then be laid out on top of this combination. The peripheral edges 140 of the cover 134 can then be clamped between the cover plate 128 and the upper edge of the bowl 126 to provide the desired seal.

The various modifications above described are intended to illustrate the fact that the concepts of this invention can be adapted in a large variety of ways in order to achieve the results of lthis invention. Any of the above described constructions are capable of achieving the desired pressure application and, in this connection, it is to be noted that the degree of pressure applied will vary depending on the nature of the parts being finished. A pressure above atmospheric is necessary although it has been found that effective pressures of a fraction of a pound per square inch have produced recognizable im- It has been found that the cutting speed effected by the finishing media varies in proportion to the amount of pressure applied although the degree of improvement `appears to decrease after a certain upper limit of pressure is reached. In the finishing of small parts in small size vibrators, increases in efficiency are less noticeable above about 2 pounds per square inch effective pressure. On larger size pieces and where large size vibrators are employed, effective pressures up to about 4 pounds per square in are contemplated. `It will be understood, however, that higher pressures could be employed although the lack of a substantial increase in efficiency generally would not warrant the use of higher pressures.

The practice of the instant invention has proven highly satisfactory for the reason that lighter media can be employed much more effectively. This feature of the invention is quite important since, in the past fine polishing requiring light media, has been an extremely slow operation. Expanded use of low density media such as felt, nylon, Walnut shells, wood and vthe like is thus made possible with the use of the system of this invention. Since lighter media can be efficiently employed, pitting and nicking of parts often associated with finishing operations can be largely avoided.

Further advantages recognized through the use o-f the instant invention relate to improvements in internal deburring and polishing of parts. Thus, it has been found that application ofV pressure in accordance with this invention permits .the finishing media t-o reach areas of parts which cannot be effectively reached by conventional techniques. Furthermore, a polishing operation employing the conceptsv of this invention will be characterized by greater efficiency both with regard to duration of the operation and with regard to the surface 4appearance of the finishe-d parts. Finally, it has been found that parts which previously required fixtures for holding them in pl-ace in the vibrating bowl do not require such fixtures When finished by means of the techniques of this invention.

The amount of processing time which can be saved in the practice of the instant invention will depend upon certain variable such `as the size and type of the parts and the type of media. Where light media are employed, the cutting speed may be increased by as much as l0 to l while in other cases an increase in the order of 2 to 1 'has been realized. Although wear of the media will also increase in proportion to the pressure, it has been found that this rate of increase in not detrimental when the increase in processing speed is considered.

In one processing operation, metallic blocks formed of 1018 cold rolled steel are vibrated with Carborundum triangle media both with and without the application of of pressure. Where no pressure was applied, the metal removal rate for a 7-hour run was 0.9876 gram per hour. With the application of 1.5 pounds per square inch pressure, the metal removal rate was 1.61129 grams per hour for a 7hour test thereby exhibiting a 1.6.3 speed in crease ratio. Media breakdown was 0.29 per-cent with no pressure application and 0.5 percent with pressure application.

In a 31/2-hour finishing operation carried out on l-inch diameter and 1% inch long blocks of 1018 cold rolled steel and employing Carborundum triangle media and cutting compounds, the following results were obtained:

Effective pressure pounds per Media wear Metal removal square inch rate percent rate grams per hour per hour An example of work that could not be satisfactorily processed by conventional vibrating but was satisfactorily cubes and steel wool plus grinding or polishing compound.

After ve hours of vibrating at l0 pressure the surface had an orange peel appearance and was not suitable for chrome plating. The surface condition had not been improved during the latter part of this test and it was concluded that a satisfactory polished surface could not be produced by prolonging the vibrating time. Using the same media and compounds but with an applied pressure of 0.31 pound per square inch, after forty-five minutes of vibrating a high polished surface suitable for chrome pla-ting was obtained.

Another example of greatly reduced processing time while producing a better finish involved finishing of pen points. Stainless steel pen points were vibrated to put a radius on the corners and to polish them. In each test the vibrating was done for an initial period with pre- `formed aluminum oxide media plus grinding compounds and then followed by subsequent polishing in the vibrator using wood cubes, Wood chips and polishing compounds. The total processing time for a satisfactory finish under zero pressure conditions was sixteen hours. With an applied pressure of 1.5 pounds per square inch for the initial cutting process and a pressure of 0.31 pound per square inch for the subsequent polishing process, the total processing time was reduced to five hours and the pen points had a much better finish than those processed without pressure.

In some cases a cheaper media can be used with pressure vibrating than that used for conventional vibrator finishing. The price of pre-formed media for example is considerably higher than for fused aluminum oxide but it cuts faster. Similarly, fused aluminum oxide costs more than quartz but it cuts faster. By choosing a cheaper media and then using pressure to speed up the cutting rate, in some cases it will be possible to make a savings on media cost and still keep the processing time the same as before.

Although there is no intention to be bound by any particular theory of operation, it would appear that pressure helps keep light weight parts submerged in the media and it helps to keep them separated from each other as they move with the mass of media in their circular path around lthe bowl such that the parts do not hit eachl other and damage their polished or finely finished surfaces. In conventional operations, it has been recognized that as the parts and media move through the bowl and emerge at the top near one side wall, there is a tendency for some parts and media to roll backwards toward said side wall instead of continuing in their normal path toward the opposite side wall. This backroll is substantially eliminated under pressure conditions.

In conventional systems it has also been found that light parts tend to ride on the surface of media and as some of the media and parts reach a bowl side wall ready to start downward in their circular path around the bowl, some of the lightweight parts riding on the surface of the media do not move downwardly immediately with the media. This slows down their orderly movement and causes parts to tend to segregate such that they can impinge upon each other. Under pressure conditions, lightweight parts are kept in a more intimate contact with the media mass and they travel with the media in a more orderly path without one part hitting another. Similarly, in the absence of pressure conditions the travel of media and parts is not so positive and parts and media tend to slow down near the ends of the bowl. Under pressure conditions the parts and media are kept moving in a more positive manner in such areas so that abrading continues at a uniform rate and parts are less likely to hit each other and damage their surfaces.

It will be understood that various changes and modifications can be made in the above described apparatus which provide the characteristics of this invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. A method for the finishing of parts wherein said parts are disposed in a bowl having an at least partially open end and wherein a solid granular finishing medium is combined with said parts in said bowl, a closure provided for said open end of the bowl, said closure being adapted to contact the combined parts and medium, and means for vibrating said bowl, said method comprising the steps of applying a force to said closure to thereby press said closure against the combined parts and medium so that said parts and medium are subjected to positive pressure Iby compression, said pressure comprising at least a fraction of a pound per square inch in excess of atmospheric pressure, vibrating said bowl to finish said parts, and maintaining the pressure on the combined parts and medium during said vibrating step.

2. A method for the finishing of parts wherein said parts are disposed in a bowl having an at least partially open end and wherein a solid granular finishing medium is combined with said parts in said bowl, a closure provided for said open end of the bowl, said closure being adapted to contact the combined parts and medium, and means for vibrating said bowl, said method comprising Ithe steps of applying a force to said closure to thereby press said closure against the combined parts and medium so that said parts and medium are subjected to positive pressure by compression, said pressure comprising a pressure in excess of atmospheric pressure between a fraction of a pound per square inch and about four pounds per square inch, vibrating said bowl to finish said parts, and maintaining the pressure on the corn-bined parts and medium during said vibrating step.

References Cited by the Examiner f UNTED STATES PATENTS 2,353,492 7/ 1944 OConnor 51-7 2,480,502 t8/ 1949 Nieder 51-7 3,013,365 12/1961 Harper 51--7 FOREIGN PATENTS 1,129,394 5/ 1962 Germany.

675,643 7/1952 `Gfreat Britain. 937,954 9/ 1963 Great Britain.

`ROBERT C. RIORDON, Primary Examiner.

JOHN C. CHRISTIE, LESTER M. SWINGLE,

Examiners. 

1. A METHOD FOR THE FINISHING OF PARTS WHEREIN SAID PARTS ARE DISPOSED IN A BOWL HAVING AN AT LEAST PARTIALLY OPEN END AND WHEREIN A SOLID GRANULAR FINISHING MEDIUM IS COMBINED WITH SAID PARTS IN SAID BOWL, A CLOSURE PROVIDED FOR SAID OPEN END OF THE BOWL, SAID CLOSURE BEING ADAPTED TO CONTACT THE COMBINED PARTS AND MEDIUM, AND MEANS FOR VIBRATING SAID BOWL, SAID METHOD COMPRISING THE STEPS OF APPLYING A FORCE TO SAID CLOSURE TO THEREBY PRESS SAID CLOSURE AGAINST THE COMBINED PARTS AND MEDIUM SO THAT SAID PARTS AND MEDIUM ARE SUBJECTED TO POSITIVE PRESSURE BY COMPRESSION, SAID PRESSURE COMPRISING AT LEAST A FRACTION OF A POUND PER SQUARE INCH IN EXCESS OF ATMOSPHEREIC PRESSURE, VIBRATING SAID BOWL TO FINISH SAID PARTS, AND MAINTAININ THE PRESSURE ON THE COMBINED PARTS AND MEDIUM DURING SAID VIBRATING STEP. 